The present invention relates to a guide wire for an intravascular catheter. More particularly, the present invention relates to a guide wire having a Doppler means positioned thereon.
With the recent marked advances in cardiac and vascular surgery, the use of cardiac and vascular catheters has increased considerably. Since these catheters must be inserted over a relatively long distance into internal sites in the body, considerable manipulation is required to maneuver a relatively long catheter into branch vessels that extend at sharp angles relative to the feeding direction of the catheter.
The most common catherization procedure is the Seldinger technique wherein an area of the skin is antiseptically prepared and a local anesthetic is applied, after which a small cut is made in the skin over the site of the vessel to be cannulated. An arterial needle assembly (inner needle, stylet) is then introduced into the vessel and its introduction is indicated by a back flow of blood to the inner needle. The inner needle is then withdrawn and replaced with a guide wire which is then introduced through a cannula for a distance of approximately 6 to 10 inches. External pressure is then applied to hold the guide wire in place while the cannula is withdrawn after which the guide wire is fed into the vessel to the selected area by fluoroscopy or some other similar technique. Considerable manipulation is required of the guide wire to direct it to the desired area. Once the guide wire reaches the selected area, the catheter is passed over the guide wire to the selected area after which the guide wire is withdrawn from the catheter. In angioplasty procedures, the technique employed is similar, however, the guide wire is not withdrawn.
Generally, the guide wires used to locate the catheter are formed of closely wound stainless steel or gold wire forming a continuous coil spring having an inner bore which is sealed at the distal end with a rounded cap or tip. Various modifications of this basic design are disclosed in, for example, U.S. Pat. Nos. 3,789,841, 4,538,622, 4,545,390 and 4,580,573.
U.S. Pat. No. 4,527,569 discloses a device for guiding a surgical needle into a blood vessel. The disclosed device contains one piezoelectric transducer acting as a transmitter and the other piezoelectric transducer acting as a receiver and requires that the transducers be aligned such that there is a point of convergence between the axis of the ultrasonic beam produced by the first transducer and the line of sight along which the second transducer receives reflected waves. The disclosed device is stated to be useful for the first part of the Seldinger technique wherein the surgical needle is introduced into the blood vessel but no mention is made of the use of the device for the introduction of the guide wire or catheter.